1. Field of the Invention
This invention relates to a blast furnace tuyere sensor system and more particularly to a novel peepsight enabling an operator to inspect the condition of the tuyeres and receipt of light from the tuyeres by one end of a fiber optic cable mounted in the peepsight and connected at the other end to an optical sensor.
2. Description of Related Art
With the advent of pulverized coal injection into blast furnaces, it becomes critical to be able to detect problem in the injection system at the tuyeres. As coal injection rates increase, furnace downtime resulting from tuyere, blowpipe, and upper assembly failure also increases, often resulting in catastrophic furnace breakouts and damage to furnace auxiliary equipment.
It is known to use a photosensitive resistor to measure the absence of light from a tuyere through which finely divided coal is being injected into a blast furnace, thereby indicating blockage of the tuyere and enabling coal flow to that tuyere to be shut off. Netherlands patent document 8,901,208 discloses such a system.
As described in a copending application, entitled "Blast Furnace Tuyere Sensor System," of the present inventors, we have found that the condition of tuyeres near to a plugged or blocked tuyere is indicative of possible failure of those nearby tuyeres. Such condition we call a "bright tuyere." We have found that a bright tuyere can be caused by several abnormal conditions, i.e. (1) a plugged injection lance, (2) sensor failure, or (3) coal in the bustle pipe of the furnace feeding air to the tuyeres. The carrying over of coal into the bustle pipe is an emergency condition which must be attended to immediately to avoid catastrophic consequences. When a tuyere shows blocked, while a downstream tuyere shows bright, the bright tuyere condition is being caused by burning coal being carried over from the blocked tuyere. A bright tuyere condition always needs to be investigated to avoid burnout of the tuyere and costly shutdown of the furnace.